Study Finds High Activity With Poziotinib in Non-Small Cell Lung Cancer with HER2 Exon 20 Insertion Mutations

New data from a trial of poziotinib in non-small cell lung cancer (NSCLC) with G778_P780dup HER2 exon 20 insertion (exon20ins) mutations found that the drug had high activity in both treatment-naïve and previously treated patients. The data are being presented at the European Society for Medical Oncology Congress 2022.

Poziotinib is a novel, oral epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) that limits the tyrosine kinase activity of EGFR as well as HER2 and HER4. This then inhibits the proliferation of tumor cells that overexpress these receptors, which has been associated with a number of different cancers, including NSCLC, breast cancer, and gastric cancer.

HER2 exon20ins mutations are a rare subset of mutations that occur in approximately 2% to 4% of NSCLC cases, according to the study. No therapies are currently approved for either treatment-naïve or previously treated NSCLC with these mutations.

The findings are based on an assessment of the activity of poziotinib in a population of previously treated (cohort 2) and treatment-naïve (cohort 4) patients with NSCLC with the G778_P780dup HER2 exon20ins mutation from the ZENITH20 clinical trial.

“The G778 mutation is one of the frequent HER2 exon 20 insertion mutations and patients with these tumors have a poor prognosis,” said Francois Lebel, MD, chief medical officer at Spectrum Pharmaceuticals, in a press release. “These findings demonstrate the high activity of poziotinib in both treatment-naïve and heavily pretreated patients.”

The previously treated patients in the ZENITH20 trial received 16 mg of poziotinib once a day, whereas treatment-naïve patients in cohort 4 received 16 mg daily or 8 mg twice a day. The primary endpoint was objective response rate (ORR).

Fourteen patients had the HER2 G778 insertion mutation and of those, 12 were evaluable. All 12 of those patients had a partial response, resulting in an ORR of 85.7% and a median duration of response of 5.5 months. The ORR was 100% in the previously treated patients in cohort 2 and 71.4% in the treatment-naïve patients in cohort 4.

Furthermore, median duration of response was 5.3 months for previously treated patients and 8.9 months for treatment-naïve patients. The frequency of adverse events (AEs) was consistent with prior reports and overall AEs were similar to the TKI class, according to the study.

REFERENCE

Spectrum Pharmaceuticals Announces Data from Poster Presentation for Poziotinib in NSCLC Patients with G778_P780dup HER2 Exon 20 Mutations at ESMO Congress 2022. News release. Spectrum Pharmaceuticals; September 10, 2022. Accessed September 12, 2022. https://investor.sppirx.com/news-releases/news-release-details/spectrum-pharmaceuticals-announces-data-poster-presentation